Liquid-core capsules for pest control

ABSTRACT

Liquid core capsules are provided for pest control, wherein the liquid-core capsules have a liquid core comprising entomopathogenic nematodes and a surrounding hydrogel shell. The liquid core comprising the nematodes is formed on the basis of an emulsion comprising at least an oil and an aqueous liquid.

The present invention relates to liquid-core capsules for pest control,wherein the liquid-core capsules have a liquid core comprisingentomopathogenic nematodes and a surrounding hydrogel shell.Furthermore, the invention relates to a method for producing suchliquid-core capsules and a method for controlling pests, in which saidliquid-core capsules are applied to a plant stock.

Nematodes (threadworms) are filamentous soil biota that have a length of0.5 mm, for example. They are among the most species-rich multicellularcreatures on earth and occur naturally in all imaginable habitats.Entomopathogenic (entomon—Greek for insect) nematodes (EPN) are thosenematodes that act as natural enemies of insects and in this caseusually use the insects as host organisms or generally damage saidinsects. In terms of biological pest control, the term entomopathogenicnematodes also includes parasitic nematodes of snails, since these arecomparable to insect-pathogenic nematodes in terms of their biology,reproduction, application and effect. The term entomopathogenicnematodes should therefore be broadened to include not only nematodesthat damage insects. In addition to the snail-damaging nematodes, thiscan also mean, for example, predatory nematodes which actively hunttheir prey, for example, other nematodes, and which are also used inbiological pest control, for example, for combating root-damagingnematodes.

Certain nematodes are often highly specialized on certain insects orsnails, so that they only infest the respective species and aretherefore harmless to humans, warm-blooded animals and plants. Thisproperty makes the entomopathogenic nematodes particularly suitable forbiological pest control.

In biological crop protection, nematodes are now among the mostimportant opponents of insects and snails that live in or on the plantsubstrate (for example, peat, compost, minerals, plastics). In thiscontext, the larval stages of many beetles (grubs) or flies (maggots)play a particularly important role, since said larval stages can causeconsiderable damage to the root region of the plant. Insects and snailsthat cause damage above ground can also be controlled with the help ofnematodes, for example, if the animals go into the ground to pupate orlay eggs, move on the ground or are accessible to the nematodes inanother way. As a rule, the entomopathogenic nematodes actively seek outtheir respective host organisms and invade said organisms, so that theinfected animals (for example, larvae) usually die within two to threedays. The nematodes then multiply in the carcasses and then infest otherliving larvae or the respective host organisms. This process continuesuntil no more living host organisms are found by the nematodes.

Entomopathogenic nematodes are already being used In biological pestcontrol, for example, to control the grubs of garden leaf beetles, Junebeetles, vine weevils and corn rootworms, and to control the maggots ofthe meadow crane fly and the fungus gnat, and to control thecaterpillars of the oak processionary moth, the codling moth and thedeltoid moths and night moths and to control thrips larvae and pupae andto control field snails and path snails (slugs). The areas ofapplication are in the care of lawns and public greenery, in treenurseries, in fruit growing, in the cultivation of vegetables, herbs andornamental plants and in maize cultivation. The nematode speciesHeterorhabditis bacteriophora, Heterorhabditis downesi, Steinernemafeltiae, Steinernema carpocapsae, Steinernema kraussei andPhasmarhabditis hermaphrodita are used in particular for these purposes.

The commercial mass production of entomopathogenic nematodes (EPN) isusually carried out by means of microbiological processes in liquidculture bioreactors (fermenters). After propagation, the nematodes areusually introduced into a clay mineral powder, for example, about7,500,000 animals/g. Said clay mineral powder serves as a carriermaterial that can be portioned in bags. It is expedient to store theproduct in a cool place at between about 4° C. and 10° C. until it isused. According to current recommendations, the preferred applicationrate for the overwhelming number of pests that can reside in the plantsubstrate is around 500,000 EPN/m².

In a conventional application, the product, that is, the mixture of EPNand clay material powder, is dispersed in water and applied to the areato be treated by watering or spraying. The amount of water required isbetween 100 and 5,000 ml/m², for example, depending on the applicationmethod, the environmental conditions and the culture to be treated. Thedispersion should be regularly stirred or shaken during application toprevent the nematodes from sinking into the dispersion. However, in thiscase, strong shearing forces should be avoided in order to not damagethe nematodes. After treatment, the plant substrate must be keptsufficiently moist during the control period, since otherwise thenematodes can dry out quickly. In addition, the nematodes cannot move ondry surfaces, making it difficult to find the hosts. However, effectssuch as the nematodes being flushed out of the soil substrate, forexample, during watering, can lead to the effect of the nematodes beingfurther reduced.

Generally, treatment with entomopathogenic nematodes is carried out atthe time of the first appearance of the pest stages to be controlled. Ifno pests are present, the entomopathogenic nematodes can usually onlysurvive in the substrate for a few days. Overall, successful treatmentwith entomopathogenic nematodes requires the right time of treatment, aneffective application method and sufficient moisture in the plantsubstrate during the entire control period. Usually, the treatment mustbe repeated at regular intervals.

There are already attempts to introduce entomopathogenic nematodes intoa plant stock in other administration forms. For example, U.S. Pat. No.4,753,799 describes an alginate-based encapsulation for nematodes. Thecapsules can be coated to reduce water loss. WO 2016/176764 A1 also hasalginate capsules with nematodes as the subject. The alginate capsulesare coated with cellulose and dried. This enables long-term storage overseveral months. The problem with such encapsulated nematodes, however,is that the effect of the released capsules in pest control is alwaysrelatively short. WO 2016/176764 A1 describes the capsules being brokendown within one day to one week. Also, the release experiments referredto in U.S. Pat. No. 4,753,799 are only carried out for a period of 24 to48 hours. At least currently there is no product on the market withparticle-like encapsulated nematodes.

In view of this, the object of the invention is to improve theencapsulation of nematodes such that the application of the nematodecapsules achieves a significantly prolonged effect in pest control.

This object is solved by liquid-core capsules with entomopathogenicnematodes, as they result from claim 1. Preferred embodiments of saidliquid-core capsules are the subject matter of the dependent claims.Furthermore, this object is solved by a method for producing suchliquid-core capsules and by a method for controlling pests, as itderives from the other independent claims and the claims dependentthereon.

The proposed liquid-core capsules for pest control have a liquid corecomprising entomopathogenic nematodes and a surrounding hydrogel shell.An important point of the invention is that the liquid core is formed onthe basis of an emulsion containing at least an oil and an aqueousliquid. Surprisingly, the inventors were able to show that, due to theemulsion in the core of the capsules, the entomopathogenic nematodes aremuch more vital and active for a longer period of time compared toconventional nematode products. This makes it possible for the nematodesto be released from the liquid-core capsules after they have beenapplied to a plant stock over a considerably longer period of time thanis possible with conventional nematode products. For example, theliquid-core capsules according to the invention allow the nematodes tobe released over a period of more than four weeks. This extends theperiod of effect accordingly. The need for further follow-up treatmentswith renewed application of the capsules during the culture period issignificantly reduced or it may even be possible to dispense withfollow-up treatments at all. The emulsion in the core also has theparticular advantage that the nematodes in the capsules are betterprotected from drying out and can therefore better survive dry phases inthe plant substrate. This results in increased effectiveness when usingthe liquid-core capsules according to the invention.

In general, the use of encapsulated nematodes has the particularadvantage that the capsules can be dosed more precisely, especially onsmall areas and in individual pots, than with a conventional wateringapplication, for example. This avoids underdosing and overdosing, whichincreases the effectiveness on the one hand. On the other hand, avoidingoverdosing results in further cost advantages. Also in comparison with,for example, a conventional watering application of nematodes, thenematodes in the liquid-core capsules are better protected againstshearing forces. There are also no changes in concentration due tosinking of the nematodes in the formulation. Furthermore, the amount ofwater used when applying the liquid-core capsules is significantly lowerthan, for example, in a watering application. Furthermore, due to theencapsulation, the water or the liquid phase remains in the immediatevicinity of the nematodes and is not distributed in the soil, as is thecase with a watering application, for example. As a result, thenematodes are better protected from drying out.

The oil content in the liquid-core capsules or the use of an emulsion inthe liquid core of the capsules according to the invention has thefurther decisive advantage that this significantly stabilizes the shapeof the capsules during production. Compared to capsules containing nooil content in the core, they have a much more even, rounder shape.Because of the reduced volume loss due to water evaporation associatedwith the emulsion, the capsules also remain dimensionally stable overthe long term. On the one hand, this is an advantage when using theliquid-core capsules in crop protection, but also when storing theliquid-core capsules before use. The inventors found that the capsulesremain dimensionally stable for months when stored in a cool place inclosed and preferably ventilated containers. The liquid-core capsulesaccording to the invention can even be stored in such containers at roomtemperature for long periods without increased loss of water. Storage atroom temperature should preferably take place with especially goodventilation. It can be useful to moisten the surface of the capsuleswith water for storage over a period of several months. A particularlylong storage is possible with cooling, for example, between 4° C. and10° C. The oxygen requirement of the nematodes is reduced under theseconditions, so that the vitality of the nematodes can be maintained overa very long period. The cooling also has the advantage that the growthof disruptive microorganisms, for example, mold, is significantly sloweddown.

The liquid-core capsules according to the invention can be used directlywithout further modifications, for example, in agriculture or inhorticulture, and can be applied to the plant stock, for example, usingmechanical means. The particularly stable shape of the liquid-corecapsules according to the invention already offers advantages when theproduct is applied mechanically, since the machinability is very goodbecause of the good stability and the resulting standardization of theproduct, for example, when applying with spreaders. As a result of thesurprisingly positive effect of the emulsion in the core of the capsuleson the vitality of the nematodes, the nematodes remain approximatelyequally active for several weeks after the liquid-core capsules havebeen applied to a plant stock, wherein the nematodes continuously emergefrom the liquid-core capsules. The effect of the nematodes on the pestsis maintained over a long period of time, for example, up to four weeks,as a result of this delayed release. On the one hand, the emulsioncontributes to this long-term effect of the liquid-core capsules in use,since this reduces water evaporation. On the other hand, the hydrogelshell offers additional protection against drying out, whereby,depending on the application, the protection of the hydrogel shellagainst drying out can be increased by further measures, for example, byincreasing the wall thickness or by using additives in the shell.

Experiments by the inventors were able to show that using an emulsion inthe core of the liquid-core capsules according to the inventionsignificantly reduces the drying out of the nematodes in the capsulecompared to a liquid-core capsule containing only water in the core(without emulsion). While a liquid-core capsule having an aqueous coredries out completely within a few hours, a liquid-core capsule accordingto the invention having a core on the basis of an emulsion remainsdimensionally stable for several days, in each case in an open system atroom temperature. Even after drying phases, which result in an almostcomplete loss of water from the capsule, a film of water remains in theimmediate vicinity of the nematodes. Comparable to a water-in-oilemulsion, the oil forms a diffusion barrier for the water. Addedemulsifiers, for example, E405, stabilize this condition. A certainminimum proportion of water in the core during the production of theliquid-core capsules, in particular at least 30%, is particularlyadvantageous since, on the one hand, this ensures a surrounding waterfilm that is necessary for the survival of the nematodes and, on theother hand, it is very expedient for the formation of the hydrogel shellfor process technology reasons. Overall, therefore, the liquid-corecapsule according to the invention containing the core based on anemulsion offers the nematodes in the core enough moisture to survive, sothat the nematodes can emerge from the liquid-core capsules over a longperiod of time during use.

The oil as a component of the emulsion is preferably a vegetable oil,for example, sunflower seed oil and/or rapeseed oil and/or olive oil.Combinations of different oils are also possible. In principle, forexample, the use of scented oils as a component of the emulsion is alsopossible. In general, oils that are liquid at temperatures above about0° C. can preferably be used. Even if the liquid-core capsules aregenerally used in plant protection at higher temperatures, the use ofoils that are still liquid at lower temperatures is advantageous for thevitality of the nematodes, in particular with regard to the storage ofthe liquid-core capsules at low temperatures, for example, atrefrigerator temperatures (4-10° C.). Oils which are preferably stillliquid at temperatures down to −15° C. or down to −20° C. are preferablyused.

Preferably, the proportion of oil in the emulsion is at least 10%.Preferably the maximum proportion of oil in the emulsion is 70% (w/w).For example, the proportion of oil in the emulsion can be 10% or 15% or20% or 30% or 40% or 50% or 60% or 70% (in each case w/w). In theproduction of the liquid-core capsules, a suspension of the nematodes orthe nematode product in water is preferably mixed with the emulsion toprovide the mixture for the core. As a result, the proportion of oil inthe core of the liquid-core capsules is generally slightly reduced.However, the proportion of oil in the liquid core should preferably notbe less than 15%. For example, the proportion of oil in the core can bein a range between 19 and 68%, in particular between 19.4 and 67.9%.

The aqueous component (aqueous liquid) of the emulsion can in particularbe water, for example, tap water, or treated water, for example,deionized water. In principle, isotonic salt solutions that correspondto the physiological osmolarity of the nematodes are further suitable.In preferred embodiments, the water for the emulsion can be enrichedwith oxygen. This can have a further beneficial effect on the vitalityof the nematodes.

The surrounding hydrogel shell is preferably an alginate shell, forexample, a calcium alginate shell. An alginate shell is particularlysuitable for the liquid-core capsules according to the invention, since,on the one hand, the production of such liquid-core capsules can beimplemented very well in terms of process technology. On the other hand,the components of the alginate shell are very easily biodegradable afterthey have been applied to a plant substrate and do not leave behind anyproblematic residues.

In particularly preferred embodiments, the liquid-core capsulesaccording to the invention comprise a capsule shell made from analginate-based hydrogel, wherein water, vegetable oil and the nematodesare located in the liquid capsule core. Salts and one or moreemulsifiers can be provided as auxiliaries. Preferably only food gradesubstances are used for the capsules so that the capsules are fullybiodegradable.

In preferred embodiments, the hydrogel shell can contain at least oneadditive. The properties of the hydrogel shell can be adapted todifferent applications by means of one or more additives, for example,further protection against evaporation being able to be ensured in thisway. Examples of suitable additives are cellulose-based compounds,preferably methyl cellulose. Other possible additives are thickenerssuch as xanthan and/or locust bean gum. Said thickeners can also be usedto advantage in order to influence the properties of the hydrogel shellin a positive way.

The individual liquid-core capsules preferably comprise an average ofabout 1,000 to 15,000 nematodes per liquid-core capsule. About 1,500 to7,500 nematodes per liquid-core capsule are particularly preferred, forexample, 2,000 to 7,500 nematodes per liquid-core capsule. It can alsobe preferred that fewer nematodes are comprised per liquid-core capsule,for example, between 1,000 and 2,000 nematodes per liquid-core capsule.For example, if the nematodes are to be applied to plant pots, it may beadvantageous to use more capsules, each with fewer nematodes, than justa few capsules, each with many nematodes. The background to this isthat, for example, in the case of mechanical dispensing, the intendednumber of capsules to be dispensed may not be met exactly. The morenematodes are contained in the individual capsule and the fewer capsulesthat are to be applied for the intended dosage, the greater the dosagedeviation if one capsule is applied too much or too little. Against thisbackground, for example, a number of 1,500 to 2,000 nematodes, inparticular approximately 1,600 nematodes, per liquid-core capsule can beparticularly preferred. In general, an exact count and dosage ofnematodes is difficult in practice, so that these specifications aresubject to certain fluctuations and is to be understood, for example, asan average deviation of ±20%. The deviations can optionally also behigher.

The liquid-core capsules can have an average diameter of, for example,between 1 to 30 mm, preferably between 3 to 10 mm or between 5 to 10 mm.The larger the capsules, the more nematodes can generally be containedin the liquid-core capsules. As already explained in connection with thenumber of nematodes per liquid-core capsule, it can also be advantageouswith regard to the size of the liquid-core capsules to make the capsulesrelatively small, so that possible dosage errors are minimized. Againstthis background, a particularly preferred size of the liquid-corecapsules is a diameter of 3 to 6 mm or 4.5±1.5 mm. The size of thecapsules can easily be controlled in the production process of theliquid-core capsules, as is explained in more detail below in connectionwith the production process for the liquid-core capsules.

The weight per liquid-core capsule is preferably on average between 10to 100 mg, preferably between 20 to 80 mg, in particular between 40 to80 mg. A weight in a range from 40 to 60 mg per liquid-core capsule isparticularly preferred, particularly preferably about 50 mg perliquid-core capsule. These specifications relate to the wet weight. Theweight of the liquid-core capsules can also be varied in the course ofthe production process of the liquid-core capsules and can thus beadapted to different types of application of the liquid-core capsules.With the size and weight, the number of nematodes per liquid-corecapsule or the loading of the liquid-core capsules with nematodes canalso be adapted to the specific application. For example, liquid-corecapsules that are placed in individual plant pots, for example, by hand,can be made larger and contain more nematodes than liquid-core capsulesthat are mechanically distributed over a large area, for example, with aspreader. Larger liquid-core capsules are generally suitable for dosingone or a few capsules, for example, three capsules per plant pot.Smaller capsules may be preferred to larger capsules with a view toreducing dosing errors, particularly when the capsules are appliedmechanically.

In a further preferred embodiment of the liquid-core capsules, theliquid-core capsules further contain at least one attractant for thepests to be controlled. An attractant ensures that the pests, that is,the target insects of the nematodes or possibly the snails, areattracted to the liquid-core capsules, so that the nematodes emergingfrom the liquid-core capsules can reach the insects or snails much moreeasily. For example, essential oils are suitable as attractants. Mintoil, which is very attractive to the larvae of the fungus gnat, hasproven to be particularly beneficial. Very low concentrations of anattractant and in particular of an essential oil are usually sufficient.For example, 0.1 to 1 ml, preferably 0.3 ml, of mint oil can be addedfor the preparation of 1 kg of liquid-core capsules, which is generallysufficient for a particularly advantageous attractant effect on thefungus gnat larvae. The attractant and in particular the essential oilcan be added, for example, during the production of the emulsion or as acomponent of the emulsion. The essential oil can be used as anadditional oil in the emulsion for this purpose.

Various nematodes are suitable as entomopathogenic nematodes in theliquid-core capsules according to the invention. For example, thespecies Steinernema carpocapsae and/or Steinernema feltiae and/orSteinernema kraussei and/or Heterorhabditis bacteriophora and/orHeterorhabditis downesi and/or Phasmarhabditis hermaphrodita areparticularly suitable. Said nematodes have already proven successful inbiological pest control and can be used very effectively to controlvarious pests. The following table summarizes the different areas ofapplication and the pests found there, with regard to the nematodespecies suitable for controlling them.

Area of application Pest Nematode species Lawn Garden leaf beetles,Heterorhabditis June beetles, May bacteriophora beetles (grubs)Heterorhabditis downesi Crane fly (maggot) Public green Oakprocessionary moth Steinernema feltiae Nurseries Vine weevil, gardenHeterorhabditis leaf beetle (grubs) bacteriophora Heterorhabditisdownesi Steinernema kraussei Fruit growing Codling moth Steinernemafeltiae (caterpillar) Vegetable, herb and Deltoid moths and nightSteinernema feltiae ornamental plant moths (caterpillar) Steinernemacarpocapsae cultivation Fungus gnat (maggot) Thrips (larva, pupa) Fieldsnails and path Phasmarhabditis snails (slugs) hermaphrodita Maizecultivation Corn rootworm (grub) Heterorhabditis bacteriophora

The liquid-core capsules according to the invention can, for example, beused with particular advantage for the encapsulation of Steinernemafeltiae, which are used to combat fungus gnats and in particular thelarvae of fungus gnats.

The invention further comprises a plant substrate that already containsthe liquid-core capsules according to the invention. Such a plantsubstrate can be used with advantage, for example, for the potting andrepotting of vegetable plants, herbs or ornamental plants, in which anemerging pest infestation is immediately controlled. This isparticularly advantageous if the plants have had contact with pestsbefore being potted or repotted. Liquid-core capsules containing arelatively high nematode density are particularly suitable for mixingthe liquid-core capsules according to the invention into a plantsubstrate. For example, liquid-core capsules containing approximately7,200 animals per liquid-core capsule can be used for this purpose. Thiscorresponds to around 50 million EPN/kg capsules. For the production ofthe plant substrate, the different, per se customary components of thesubstrate (for example, white peat, black peat, water, carbonate oflime, fertilizer, wetting agent) can be mixed and proportionately mixedwith, for example, approximately 100 g capsules per m³ substrate.

The invention further comprises a method for producing liquid-corecapsules according to the above description, wherein the liquid-corecapsules to be produced have a liquid core comprising entomopathogenicnematodes and a surrounding hydrogel shell and the liquid core areformed on the basis of an emulsion comprising at least an oil and anaqueous liquid. For the production of said liquid-core capsules, theemulsion comprising the nematodes is dropped into a hydrocolloidsolution in the presence of divalent ions. This method, known inprinciple as inverse microencapsulation, allows the production ofliquid-core capsules comprising nematodes in the liquid core, thenematodes being characterized by a particularly long-term vitality andactivity over several weeks during the use of said liquid-core capsulesin pest control. This production process allows the capsule size andweight to be controlled and the nematode loading of the capsules to beadjusted so that the liquid-core capsules can be adapted to differentapplications.

Overall, the liquid-core capsules that can be produced using thisprocess offer a continuous supply of nematodes in the plant substratefor biological pest control and thus effective protection of the plantstock for several weeks. Since the nematodes can continuously emergefrom the liquid-core capsules over a longer period of time, the use ofsaid liquid-core capsules has a long-term effect. The structure of thecapsules and in particular the emulsion comprised in the liquid coreleads to a delayed drying out of the nematodes, so that living andactive nematodes can emerge from the capsules for weeks, thus beingcontinuously released. In addition, the liquid-core capsules producedaccording to the invention offer good mechanical stability, which allowseasy handling and good shelf life without mold growth. The method alsooffers the advantage that the capsules can be adapted to differentrequirements, in particular by adapting the hydrogel shell. For example,the wall thickness of the shell and its strength can be influenced byadditives. The use of the liquid-core capsules in the plant stock allowsa largely constant concentration of nematodes in the plant substratebecause of the constant conditions for the nematodes due to the emulsioncomprised in the liquid-core capsules and the long-term or delayedrelease of the nematodes, even with effects such as a washing out of thenematodes that have already left the soil substrate, for example, inebb/flow systems in plant culture.

For the production of the liquid-core capsules the material for theshell is provided as a hydrocolloid solution. The liquid for the core isdropped into said hydrocolloid solution. The hydrocolloid solutionpreferably comprises alginate, in particular sodium alginate (E401) andoptionally further additives. The liquid for the core preferablycomprises divalent ions, in particular calcium ions, for example, in theform of calcium chloride or calcium lactate. Calcium chloride or calciumlactate can be added, for example, in a concentration of at least 1% byweight and at most 5% by weight. Good encapsulation results aregenerally achieved, for example, with 1% by weight of calcium chloride.When said liquid for the core is dropped into the alginate solution, ashell forms spontaneously around the drops entering the hydrocolloidsolution. The alginate solution can comprise, for example, between 0.5and 5% by weight of E401, preferably 1% by weight of E401 in water.Methyl cellulose and/or xanthan gum and/or locust bean gum, for example,can be added as additives or stabilizers. Even in very lowconcentrations, said additives have very good effects on stabilization,for example, the additives can be added in concentrations between 0.125%by weight up to 1% by weight, wherein xanthan gum and locust bean gumachieve good effects even in very low concentrations and methylcellulose in somewhat higher concentrations.

The liquid for the core is based on the emulsion (oil and aqueousliquid, for example, water) and the nematodes to be added. For example,the nematodes can be suspended in water and added to the emulsion. Theemulsion is preferably prepared with a proportion of the oil between 20%and 70% and water. The water can be tap water, but also, for example,treated water, such as ultrapure water or fully deionized water. Forexample, isotonic salt solutions can also be used instead of water.Various oils or liquid edible fats can be used as oils, in particularsunflower seed oil, rapeseed oil, olive oil or others. Special oils suchas scented oils can also be used as the oil or as a component of the oilfraction. It is advantageous to add emulsifiers, such as sunflowerlecithin, soya lecithin, propylene glycol alginate (E405), silica sol orothers to stabilize the emulsion. The emulsion itself can be prepared byrapid stirring. It is particularly advantageous to use a dispersingdevice, for example, an ULTRA-TURRAX® (IKA-Werke GmbH & Co. KG, Germany)or similar devices.

In principle, commercially available nematode products can be used forthe production of the liquid-core capsules, said products being offered,for example, with clay mineral powder as a carrier or other carriermaterials. Oil-based nematode products can also be used for theliquid-core capsules according to the invention. For this purpose, therespective nematode product can, for example, be suspended in water andmixed with the previously prepared emulsion of oil and water until ahomogeneous mixture is formed. Divalent ions can be added to saidmixture, for example, by adding calcium chloride or calcium lactate, andsaid mixture is then added dropwise to the hydrocolloid solutionprovided. After the core liquid has been dropped into the hydrocolloidsolution and after the hydrogel shells have formed around the drops, theresulting liquid-core capsules can be sieved off and rinsed with water.

The liquid-core capsules produced can be stored for a long period oftime, for example, at least up to 2 months, refrigerated storage beingpreferred. The nematodes remain vital over a very long period of time,especially if they are stored in a cool place. Of course, theliquid-core capsules produced can also be used more or less immediatelyfor biological pest control. Storage at room temperature over a longerperiod of time, for example, up to 6 weeks, is also possible.

The invention also comprises a method for controlling pests, in whichthe liquid-core capsules described above are applied to a plant stock.In addition, the invention comprises the use of the describedliquid-core capsules for pest control. The particularly advantageousproperties of the liquid-core capsules described are evident in thismethod of controlling pests, since the emulsion comprised in the core ofthese capsules enables the capsules to have a very long-term effect incontrolling pests. The emulsion in the core leads to the capsulesremaining stable over a long period of time due to reduced evaporation,and the emulsion also having a very positive effect on the vitality ofthe nematodes, so that long-term release and activity of the nematodesare also guaranteed. Overall, this leads to active nematodes emergingfrom the capsules over a period of several weeks, for example, up tofour weeks, and being able to have a damaging effect on their respectivetarget insects or possibly on the snails.

The liquid-core capsules are expediently introduced onto or into theplant substrate for use in pest control. The introduction can be done indifferent ways. In the simplest case, the liquid-core capsules arespread manually and optionally incorporated into the substrate orcovered by a further layer of substrate that is spread on. For example,the liquid-core capsules can be incorporated into the top tencentimeters of the substrate layer. In general, it is advantageous ifthe liquid-core capsules are evenly distributed in the substrate layer.Technical means can also be used to place or apply the liquid-corecapsules, for example, commonly used planting or fertilizer technology,for example, seeders, fertilizer spreaders, fertilizer lances, pottingmachines or substrate mixers. In a particularly advantageous embodimentof the method for controlling pests, the liquid-core capsules can alsobe mixed into the plant substrate in an initial treatment before theplanting or sowing of the crop. This embodiment can be used with greatadvantage, for example, in the cultivation of herbs. Here, the nematodesare deposited in the form of the liquid-core capsules in the plantsubstrate. When the plants have grown after one to two weeks and thefirst pests appear, the entomopathogenic nematodes are already present.This is also a particular advantage of the liquid-core capsulesaccording to the invention, since the long-term and delayed release fromthe liquid-core capsules over several weeks makes such a prophylactictreatment possible in the first place.

Overall, the liquid-core capsules according to the invention enable amethod for controlling pests that offers considerable advantages. Inparticular, the number of necessary treatments is reduced with theamount of work thus being reduced. An increased degree of effectivenessand increased effect safety are achieved using the liquid-core capsulesaccording to the invention. Particularly preferred areas of applicationare found in particular in the commercial cultivation of herbs andornamental plants, for example, orchids or poinsettias. The liquid-corecapsules can also be used with particular advantage in the hobby sector,in particular with potted plants. Here, the liquid-core capsules caneither be applied only after an infestation has occurred or alreadyprophylactically, for example, when the respective plants are sowed orplanted, by mixing said capsules into the plant substrate. A plantsubstrate into which the liquid-core capsules according to the inventionhave already been mixed can preferably also be used for this purpose.

Preferably, between 1-1,000 liquid-core capsules/m² substrate area areused when applying the liquid-core capsules to the plant stock.Preferably, between 10-500 liquid-core capsules/m² substrate area can beused. In general, the dosage of the liquid-core capsules depends ontheir size and their nematode load, which, as explained above, can beadjusted accordingly by adaptations in the production process. Forexample, the capsules can be produced such that there are around 50million EPN in 1 kg of capsules. Arithmetically, the average number ofcapsules here, depending on the loading of the individual capsules withEPN, is around 6,900 pieces/kg. There are about 7,200 EPN in eachcapsule on average. With a preferred application rate of 500,000 EPN/m²,10 g/m² or correspondingly 69 pieces/m² of capsules are applied.

In a particularly preferred manner, the liquid-core capsules accordingto the invention are provided in a packaging unit with approximately 50million EPN. The 50 million EPN can be encapsulated in around 32,000individual capsules and provided as a packaging unit with a wet weightof around 1.6 kg. In this case, each capsule contains around 1,500 to1,600 EPN. Such a packaging unit is generally sufficient for thetreatment of a cultivation area of around 100 m² or for around 2.5 m³ ofplant substrate or for the treatment of around 5,000 plant pots having amaximum filling volume of 1 l. This dosage specification is particularlysuitable for a light initial infestation or preventive treatment.Depending on the pest infestation and crop management, a differentdosage, in particular an increase in dosage, can be advantageous.

An even distribution of the liquid-core capsules is advantageous whenmixing the liquid-core capsules into a plant substrate. If theliquid-core capsules are placed directly on the plant substrate, it isadvantageous to cover the liquid-core capsules with plant substrate, forexample, with a layer thickness of at least 2 cm.

If the liquid-core capsules are to be introduced directly in a plantpot, an average of 6-7 capsules (corresponding to around 10,000nematodes) can be used for a plant pot having a maximum filling volumeof 1 l. The dosing can be made, for example, using a dosing spoon havinga volume of about 1 ml.

Since the production of the liquid-core capsules allows the loading ofthe nematodes per capsule to be adapted, the loading of the liquid-corecapsules with nematodes can be adjusted to the desired number ofcapsules to be released. If, for example, 3 liquid-core capsules are tobe introduced into a planter (for example, 12×12×12 cm), of which thereare around 70 per square meter, around 210 capsules/m² are required.With unchanged capsule weight and preferred application amount, theconcentration in the capsules is 16.5 million EPN/kg or 2,400 EPN/piece.

The soil temperature when applying the liquid-core capsules according tothe invention should expediently not be below 4° C. For example, thecapsules of the invention can be applied with good results when the soiltemperature is at least 8-12° C. On the other hand, the soil temperatureshould not be above 34° C.

Further features and advantages of the invention result from thefollowing description of embodiments in connection with the drawings.The individual features here can each be implemented individually or incombination with one another.

In the drawings it is shown:

FIG. 1 Diagram of the weight loss of the liquid-core capsules (emulsioncapsules) according to the invention in comparison with liquid-corecapsules containing an aqueous core (water capsules) at 22° C. and 40%relative humidity;

FIG. 2 Diagram of the weight loss of the liquid-core capsules (emulsioncapsules) according to the invention in comparison with liquid-corecapsules containing an aqueous core (water capsules) at 25° C. and 70%relative humidity;

FIG. 3 Diagram of the weight loss of the liquid-core capsules (emulsioncapsules) according to the invention in comparison with liquid-corecapsules containing an aqueous core (water capsules) at 4° C. and 40%relative humidity;

FIG. 4 Vitality profile of the nematodes encapsulated according to theinvention after application in a plant substrate;

FIG. 5 Comparison of the vitality of the nematodes in liquid-corecapsules according to the invention (emulsion capsules) and inliquid-core capsules containing an aqueous core (water capsules) overtime at 100% relative humidity;

FIG. 6 Effect of the nematodes (Steinernema carpocapsae) encapsulatedaccording to the invention on mealworms as a reference organism incomparison with a watering application of the nematodes; and

FIG. 7 Effect of the nematodes (Steinernema feltiae) encapsulatedaccording to the invention on mealworms as a reference organism incomparison with a watering application of the nematodes.

EXAMPLARY EMBODIMENTS EXAMPLE 1 Production of the Liquid-Core Capsules

A preferred production process for the liquid-core capsules according tothe invention is described in the following example. A Rotarus®multi-channel peristaltic pump having eight hoses (Hirschmann, Germany),two magnetic stirrers, stands, a dispersing device (ULTRA-TURRAX®,IKA-Werke GmbH & Co. KG, Germany), a mechanical stirrer, beakers and asieve are provided for dripping and rinsing the capsules. Alternatively,drop formation by means of nozzles is also suitable for the productionof the liquid-core capsules, in particular for the production of theliquid-core capsules on a larger scale.

In a preferred embodiment, 250 g of sunflower seed oil and 500 g ofwater are weighed out for the production of about 1 kg of liquid-corecapsules and an emulsion is produced by means of ULTRA-TURRAX®. Anemulsifier (1.2% by weight E405) is added to stabilize the emulsion.Furthermore, 3% by weight of calcium chloride is also added. Acommercially available nematode product containing 50 million animals issuspended in 20 ml of water in a separate beaker. The nematode supplyvessel is rinsed with 10 ml of water and both suspensions are combined.The 30 ml of the liquid having the nematodes are added to the emulsionand gently stirred in until a homogeneous mixture is formed. The vesselcontaining the resulting liquid for the core is attached to a stand, theeight hoses of the multi-channel pump being immersed in the liquid inthis vessel.

The water used to produce the liquid for the core can be enriched withoxygen. This can have a further beneficial effect on the vitality of thenematodes. The water enriched with oxygen can be produced to make theemulsion and/or the suspension of the nematodes.

1% by weight of sodium alginate (E401) is dissolved in water to preparethe hydrocolloid solution for the shell. Additives or stabilizers areoptionally added, for example, methyl cellulose. The liquid for the core(emulsion containing nematodes) is pumped by means of the peristalticpump for the dropping process. The outlet openings or their diameter canbe adjusted depending on the desired droplet size, wherein differenthose variants and/or additional elements such as pipette tips can beused. The height of the hoses above the provided solution can be varieddepending on the drop weight in order to obtain round capsules that areas homogeneous as possible. The drop weight can be between 10 and 90 mg,for example. The diameter of the capsules can vary from a fewmillimeters to a few centimeters. The capsule shell forms immediatelywhen the liquid for the core is dropped into the provided hydrocolloidsolution. The calcium in the core liquid reacts immediately with thealginate in the provided solution. This forms the shell and the shape ofthe drop is directly stabilized. The thickness of the shell can beadjusted depending on the ratio of calcium to alginate, optionally plusadditives. The dwell time of the capsules in the provided solution afterbeing dropped in can also be used to influence the shell thickness. Thereaction ends when all free calcium ions are consumed, or the reactionis terminated by sieving the capsules and then rinsing them with water.The capsule shell can then optionally be further solidified. Forsolidification, the capsules can be placed in a CaCl₂ bath, for example,so that the hydrogel shell is saturated with calcium ions and therebyhardened. The liquid-core capsules are then ready for use or can bestored. The liquid-core capsules are expediently portioned, packaged andlabeled for transport.

The liquid-core capsules produced in this way were examined with regardto water loss or drying out in comparison with liquid-core capsulescontaining an aqueous core. The aqueous core here means that apart fromthe nematodes, only water is contained in the core. The water loss wasdetermined from the measured weight loss of the capsules. For theseexperiments, the capsules were placed in petri dishes and exposed to therespective conditions with regard to temperature and humidity. FIG. 1shows the water loss of the liquid-core capsules at 22° C. and 40%relative humidity, FIG. 2 shows the water loss of the liquid-corecapsules at 25° C. and 70% relative humidity and FIG. 3 shows the waterloss of the liquid-core capsules at 4° C. and 40% relative humidity. Ineach case, the course of the water loss is shown for the liquid-corecapsules (emulsion capsule) according to the invention and liquid-corecapsules containing water in the core (water capsule). In all theconditions tested, it can be clearly seen that the drying out of theliquid-core capsules according to the invention is less than that of theliquid-core capsules containing water in the core. For example, for thewater capsules at 22° C. and 40% humidity (FIG. 1 ), a weight loss of80% is already achieved after 4 h. With the emulsion capsules, a weightloss of just under 80% can only be observed after 24 h. The weight lossis due to the evaporation of water from the shell and core. With thewater capsules, a water or weight loss of almost 100% can be observedafter 24 h. So by this point, the water capsules have, in a sense, driedup and shrunk greatly to a raisin-like shape. Even after 48 h, theemulsion capsules only show a weight loss of just under 80% and areround to oval in shape. This means that there is still a liquid portionin the emulsion capsules at this point in time, which is largely formedby the oil portion of the emulsion. The decisive factor here is that thevitality of the nematodes is still present at this point in time, asobserved microscopically. The vitality of the nematodes can be tracedback to the water that is still present, since said nematodes must besurrounded by at least a thin film in order to survive. However, thenematodes in the dried-out water capsules were no longer vital at thispoint in time. A very similar course was observed under the conditionsof 25° C. and 70% humidity (FIG. 2 ), wherein the maximum evaporationwas somewhat lower in both the water capsules and the emulsion capsules.At 4° C. (FIG. 3 ), the overall evaporation was significantly delayedfor both capsule types.

When evaluating these test results, it should be noted that theexperimental arrangement does not reflect the conditions for using theliquid-core capsules in a plant stock. In a plant stock, a certaindegree of moistening of the liquid-core capsules is or should generallybe ensured, so that complete evaporation of the aqueous portion shouldnot occur. As the inventors were able to show in application experimentsin plant cultures, the emulsion capsules show their effect over severalweeks, in which nematodes leave continuously. Nevertheless, even underdry conditions, there would be a clear advantage of the emulsioncapsules over water capsules, since the nematodes are still surroundedby a film of water by means of the water-in-oil emulsion and retain acertain level of vitality when the capsules are maximally dehydrated.

EXAMPLE 2 Examination of the Course of Vitality of the NematodesEncapsulated According to the Invention After Application in a PlantSubstrate

Emulsion capsules were produced with Steinernema carpocapsae accordingto Example 1 and mixed with a commercially available plant substrate(Floradur® B Seed, Floragard Vertriebs-GmbH, Germany). After thisapplication, the plant substrate was kept permanently moist at 25° C.and the vitality of the nematodes was observed for 35 days. For eachtime point examined, 4 Petri dishes, to which 3 capsules had been addedin each case, were set up with substrate. The evaluation was carried outmicroscopically by examining the substrate, wherein the ratio of thevital nematodes to the recognizable nematodes was determined overall.The measuring points in FIG. 4 represent mean values of the 4 shellsconsidered in each case. The line represents a regression line. Onaverage, the investigation shows a certain decrease in the vitality ofthe nematodes over a period of 35 days, the vitality dropping fromaround 85% at the beginning to around 60% after 35 days. Nevertheless,even after 35 days, a significant proportion of vital nematodes arestill present in the emulsion capsules.

EXAMPLE 3 Comparative Examination of the Vitality of the Nematodes inLiquid-Core Capsules (Emulsion Capsules) According to the Invention andin Liquid-Core Capsules Containing an Aqueous Core (Water Capsules) OverTime at 100% Relative Humidity

Nematodes (Steinernema carpocapsae) (emulsion capsules) encapsulatedaccording to the invention according to Example 1 and capsules having anexclusively aqueous core (water capsules) produced in a comparablemanner were observed in Petri dishes (d=90 mm) at 25° C. and about 100%relative humidity over a period of 22 days. The proportion of vitalnematodes compared to the total proportion of nematodes was determinedmicroscopically after 7 days, 14 days and 22 days. The results are shownin FIG. 5 . Under the conditions set here (100% relative humidity), thecapsules do not dry out significantly. Nevertheless, a clear differencein the vitality of the nematodes can be determined after just 7 days.While a vitality of about 90% can be observed in the emulsion capsules,only 70% of the nematodes are vital in the water capsules. After 14days, the vitality of the nematodes in the water capsules has dropped to0%. The vitality of the nematodes in the emulsion capsules is still 80%at this point in time, but then drops to 10% by day 22. These resultsshow that the oil content itself in the liquid-core capsules accordingto the invention exerts a positive effect on the vitality of thenematodes, regardless of its positive influence on drying out.

EXAMPLE 4 Examination of the Effect of the Nematodes EncapsulatedAccording to the Invention (Steinernema carpocapsae, Steinernemafeltiae, Heterorhabditis bacteriophora) on Mealworms as a ReferenceOrganism in Comparison with a Watering Application of the Nematodes

An experiment was carried out to investigate the effect of the nematodesencapsulated according to the invention (Steinernema carpocapsae) incomparison with a watering application of the nematodes. The effect onmealworms was examined for this purpose. Mealworms (larvae of the flourbeetle Tenebrio molitor) are an established reference organism foranalyzing the effects of entomopathogenic nematodes (EPN). For theexperimental arrangement, 1 l of plant substrate (Floradur® B Seed,Floragard Vertriebs-GmbH, Germany) was loosely poured into rectangulartrays 170×130×120 mm (L×W×H). 55,000 EPN in liquid were poured onto thesubstrate for the liquid application (positive control). The liquid usedfor this test was the emulsion which represented the core solution inthe production of the liquid-core capsules according to the invention.As the negative control the substrate was not treated further. For theapplication of the nematodes encapsulated according to the invention, anaverage of 12 capsules having a total of 55,000 EPN, which had beenproduced according to Example 1, were mixed into the substrate. 40mealworms were then placed on the substrate. Because thenon-encapsulated core solution, so to speak, was used for the suspensionof the nematodes in the positive control, the approach using thewatering application and the approach using the nematode capsulesaccording to the invention differs solely in the capsule form of thenematode preparation. The experimental arrangement was observed over aperiod of 6 weeks, all mealworms being removed weekly and replaced withnew mealworms (40 mealworms per batch). The nematodes were applied onlyonce at point in time zero.

FIG. 6 shows the experimental results, wherein the individualmeasurement points represent the average mortality of the mealworms inpercent (degree of effectiveness). The lines represent polynomialregressions. The sample size for the negative control was n=53, for thepositive control n=33 and for the approach using the nematodesencapsulated according to the invention n=39. This means that a total of53 experimental batches were evaluated for the negative control, a totalof 33 experimental batches were evaluated for the positive control and atotal of 39 experimental batches were evaluated for the approach usingthe nematodes encapsulated according to the invention. In weeks 1 and 2(W 1 and W 2), after the application of the EPN, there was still nodifference between the watering application (positive control) and theapplication of the liquid-core capsules according to the invention. Inweek 3 (W 3), however, only 60% mortality of the mealworms can beobserved in the watering application, whereas the mortality of themealworms in the liquid-core capsules according to the invention isstill in the range of 90%. In the following weeks, the effect of thenematodes from the watering application on the mealworms decreasessignificantly and by week 6 (W 6), it falls to only 10%, whichcorresponds to the negative control without any application ofnematodes. The effect of the liquid-core capsules according to theinvention at time W 6, on the other hand, is still present with amortality of about 55%. Overall, therefore, the application of the EPNin the form of the liquid-core capsules according to the invention isclearly superior to a watering application.

Emulsion capsules having Steinernema feltiae and Heterorhabditisbacteriophora were produced in a corresponding manner according toExample 1 and the effect of the emulsion capsules on the mortality ofmealworms as a reference organism was examined according to theexperimental approach described above.

FIG. 7 shows the experimental results with Steinernema feltiae, theindividual measurement points representing the mean mortality of themealworms in percent (degree of efficiency). Liquid-core capsules havingSteinernema feltiae were examined in comparison to an untreated variant(negative control) and a variant applied as a watering formulation(positive control). Test conditions: 40 mealworms, 1 liter substrate,200 cm² area, 2 liter vessel, 25° C. A summary of 47 test series inthree repetitions is shown. The filled circles represent the meanmortality after application of 20 capsules with a total of approximately31,000 EPN. The filled rectangles represent the mean mortality afterapplication of approximately 31,000 EPN in liquid (wateringformulation). The filled triangles represent the mean mortality withoutapplication of EPN. The lines show the polynomial regressions of therespective measurement points.

It was also shown here (comparable to FIG. 6 ) that the application ofthe EPN in the form of the liquid-core capsules according to theinvention is clearly superior to a watering application.

Liquid-core capsules according to the invention were also producedaccording to Example 1 using Heterorhabditis bacteriophora and examinedwith regard to their effect on mealworms (data not shown). In the firstexperiments, the effect of the liquid-core capsules was at leastcomparable to the watering application of the nematodes, so that theresults show that Heterorhabditis bacteriophora can also be appliedeffectively in the form of the liquid-core capsules according to theinvention and the special advantages of the liquid-core capsulesaccording to the invention can thus be used, for example, with regard toshelf life and with regard to the special advantages during applicationin comparison with the conventional watering application.

EXAMPLE 5 Application of Liquid-Core Capsules in Plant Culture

For the following application examples, capsules are provided with anaverage nematode density of around 2,400 animals (Steinernemacarpocapsae or Steinernema feltiae) per liquid-core capsule. Thiscorresponds to around 16.5 million EPN/kg capsules.

For the first application, plant pots measuring 12×12×12 cm (forexample, Göttinger square container) are filled with plant substrate(for example, “Floradur® B Seed” from Floragard) to a height of about 8cm. The seedlings (for example, young cucumber plants) are placedtherein or, alternatively, seeds of plants to be cultivated (forexample, parsley) are spread on. Three liquid-core capsules are spreadonto the substrate surface and the pots are then covered with a furthersubstrate layer of about 2 cm. In principle, all conceivable methods,with which the liquid-core capsules can be worked into the substratemanually or mechanically in a comparable manner, can be used. Incommercial plant production, the liquid-core capsules are particularlypreferably incorporated into the substrate by machine. For example, thecapsules can be injected into the substrate using fertilizer lances.This method is preferably suitable for application in individualvessels. The capsules can be spread onto the substrate and then coveredwith a further layer of substrate by means of so-called potting machinesor sowing devices.

After application, the substrate is watered with sufficient water sothat it is evenly moistened. Further plant cultivation takes place inthe usual way, according to the required plant-specific conditions. Inparticular, prolonged dry phases in the substrate should be avoided overthe entire cultivation period.

For a cultivation period of more than 4 weeks and a persistent pestinfestation, follow-up treatment is preferably carried out at four-weekintervals. About three capsules are spread on a plant pot and gentlyworked into the substrate with a small rod or a spoon, for example, sothat the capsules are covered by about 1 to 2 cm of substrate.Alternatively, a planting stick can press a hole in the substrate, forexample. The liquid-core capsules are then inserted and the holes closedagain with some substrate.

The liquid-core capsules can also be used in the same way with all knownorganic or artificial plant substrates, substitutes (for example,expanded clay, vermiculite, perlite, rock wool, foam materials) or anycustomary mixtures of different substrates and substitutes.

EXAMPLE 6 Application of the Liquid-Core Capsules in Foam Elements forPlant Culture

For these application examples, capsules with an average nematodedensity (Steinernema carpocapsae or Steinernema feltiae) ofapproximately 2,400 animals per liquid-core capsule are provided. Thiscorresponds to around 16.5 million EPN/kg capsules.

When cultivating plants (for example, orchids) in cylindrical foamelements (for example, diameter 7 cm), the foam elements are cutvertically up to about the central axis. A shoot section is insertedinto the resulting notch together with 1 to 2 capsules. The foam elementis then slightly compressed and placed in a suitable vessel (forexample, round pots, diameter 6 cm), which prevents it from expandingagain and thus provides the shoot with sufficient support.

After application, the foam element is watered with sufficient water sothat it is evenly moistened. Further plant cultivation takes place inthe usual way, according to the required plant-specific conditions. Inparticular, prolonged dry phases in the substrate should be avoided overthe entire cultivation period.

For a cultivation period of more than 4 weeks and a persistent pestinfestation, follow-up treatment is preferably carried out at four-weekintervals. To do this, the foam elements are removed from the planter,two liquid-core capsules are inserted into the notch, slightly pressedtogether and placed back into the planter.

EXAMPLE 7 Application of the Liquid-Core Capsules in the Production ofSubstrate for Plant Culture

For this application example, capsules with an average nematode density(Steinernema carpocapsae or Steinernema feltiae) of approximately 7,200animals per liquid-core capsule are provided. This corresponds to around50 million EPN/kg capsules.

During the production of substrate (for example, “Floradur® PotCyclamen/Poinsettia” from Floragard), in which the different componentsare mixed (white peat, black peat, water, carbonated lime, fertilizer,wetting agent), approximately 100 g capsules per m³ of substrate areintroduced into the mixing process. The final mixture is preferablydelivered from the substrate manufacturer to the user within a week.Users are, for example, companies that produce ornamental plants. Thetype of delivery takes place in the conventional manner as bagged goodsor as loose goods. The user processes the substrate in the usual way,preferably within 2 weeks, for example, for repotting cyclamen, pottedroses, poinsettias or hydrangeas in plant pots 12×12×12 cm. Afterprocessing, there is an average of 7,200 EPN in a pot, partly present inthe capsule and partly already distributed in the substrate.

EXAMPLE 8 Application of the Liquid-Core Capsules to Control Snails

Capsules containing nematodes of the species Phasmarhabditishermaphrodita with a density of preferably about 1,000 animals perliquid-core capsule are provided. This corresponds to around 7 millionEPN/kg capsules. The amount is sufficient to treat about 100 m² ofcultivated area.

Ideally, the application should take place at a time when snails aremore common, for example, in warm, humid weather and little sunlight.For application, the liquid-core capsules are spread on the soil of theculture area to be treated. This can be done by hand in the simplestcase and for small areas. Suitable technical means, for example,commercially available fertilizer or seed spreaders, can be used forlarger areas. The liquid-core capsules are preferably applied whereincreased snail movements are to be expected, thus, for example, aroundthe crops (for example, lettuce), between the rows of plants, on theedges of the crop area and on the edges of neighboring areas that areattractive for snails, into which the snails often retreat during theday and when it is dry. The culture area is kept moist afterapplication.

For a cultivation period of more than 3 weeks and a persistent snailinfestation, follow-up treatment is preferably carried out at three-weekintervals. The follow-up treatment is carried out in the same way aspreviously described.

EXAMPLE 9 Use of Steinernema feltiae in the Form of Liquid-Core Capsulesfor Controlling the Larvae of Fungus Gnats in the Home and Garden or inCommercial Horticulture

Liquid core capsules containing the nematodes Steinernema feltiae wereproduced in principle according to Example 1, the material compositionof the liquid-core capsules shown in the table below having been set:

Weight percentage of total Designation E number mass [%] Desalinated tapwater — 72.8 Sunflower oil — 22.1 Nematodes (product — 3.7 nemaplus ®,e-nema GmbH, Germany) Calcium chloride E509 <1 Propylene glycol alginateE405 <1 (dissolved) Sodium alginate (natural E401 <1 substance)

Packaging units containing 50 million nematodes were provided for use incommercial horticulture, for example. Each packaging unit comprisedabout 32,000 individual capsules with a total weight (wet weight) ofabout 1.6 kg, said weight having been subject to certain fluctuationsdue to different amounts of water adhesion. The capsule size had anaverage diameter of 4-5 mm and the pouring properties of the capsulesshowed good flowability.

The primary packaging was in foil bags or vessels made of plastic whichwere provided with small holes on one side for oxygen supply to thenematodes. The filling level of the liquid-core capsules was between 5and 10 cm.

Dark and cool storage (4-10° C.) was suitable as storage conditions. Theshelf life was at least 2 months. During storage, regular mixing of thecapsules, for example, by turning the vessels or bags several times, isrecommended in order to optimize the oxygen supply to the nematodes. Itwas recommended not to cover the perforated areas of the packaging forlonger periods and to let the water that emerged from the packagingdrain off.

The capsules were introduced in the plant substrate or in the seed holewhen the seeds were sown or seedlings were planted. With substratemixtures, about 50 million nematodes were used for 2.5 m³ of substrateand were evenly distributed in the substrate. Alternatively, capsuleswere placed directly in the plant pot, for example, in the seed hole,wherein an average of 6-7 capsules, that is, around 10,000 nematodes perpot, were used per plant pot with a maximum filling volume of 1 l.Alternatively, the capsules were applied to the plant substrate andcovered with at least 2 cm of substrate. The plant substrate was keptculture-moist during use.

These amounts were used for a light initial infestation or preventativetreatment.

After introducing the capsules in the plant substrate, the shell of thecapsules became permeable after about 1 week and the nematodes graduallymigrated. Over a period of several weeks, more and more new nematodesgot into the substrate and were able to effectively control fungus gnatsthe first time they appeared. In comparison to the application ofnematodes by watering application, the treatment with the capsules hadan almost doubled duration of action and could therefore also have apreventive effect against the larvae of the fungus gnat. The duration ofaction was about 6 weeks, the highest effectiveness observed between the2nd and 4th week after application.

1. Liquid-core capsules for pest control, wherein the liquid-corecapsules have a liquid core comprising entomopathogenic nematodes and asurrounding hydrogel shell, wherein the liquid core is formed on thebasis of an emulsion comprising at least an oil and an aqueous liquid.2. The liquid-core capsules according to claim 1, wherein the at leastone oil is a vegetable oil, preferably sunflower seed oil and/orrapeseed oil and/or olive oil.
 3. The liquid-core capsules according toclaim 1, wherein the proportion of oil in the emulsion is at least 10%and at most 70% (w/w).
 4. The liquid-core capsules according to claim 1,wherein the surrounding hydrogel shell is an alginate shell, inparticular a calcium alginate shell.
 5. The liquid core capsulesaccording to claim 1, wherein the hydrogel shell comprises at least oneadditive, in particular a cellulose-based compound, preferably methylcellulose, and/or at least one thickener, preferably xanthan and/orlocust bean gum.
 6. The liquid-core capsules according to claim 1,wherein the liquid-core capsules comprise an average of 1,000 to 15,000nematodes per liquid-core capsule, preferably 1,500 to 7,500 nematodesper liquid-core capsule, particularly preferably 1,500 to 2,000nematodes per liquid-core capsule.
 7. The liquid core capsules accordingto claim 1, wherein the liquid-core capsules have an average diameter ofbetween 1 to 30 mm, preferably between 3 to 10 mm, particularlypreferably 3 to 6 mm.
 8. The liquid-core capsules according to claim 1,wherein the liquid-core capsules have an average weight per liquid-corecapsule of between 10 to 100 mg, preferably between 40 to 80 mg,particularly preferably 40 to 60 mg.
 9. The liquid-core capsulesaccording to claim 1, wherein the liquid-core capsules further compriseat least one attractant for the pests to be controlled, preferably atleast one essential oil.
 10. The liquid-core capsules according to claim1, wherein the nematodes are representatives of the species Steinernemacarpocapsae and/or Steinernema feltiae and/or Steinernema krausseiand/or Heterorhabditis bacteriophora and/or Heterorhabditis downesiand/or Phasmarhabditis hermaphrodita.
 11. A plant substrate, wherein theliquid-core capsules according to claim 1 have been added thereto.
 12. Amethod for the production of the liquid-core capsules according to claim1, wherein the emulsion comprising the nematodes is dropped into ahydrocolloid solution in the presence of divalent ions.
 13. The methodaccording to claim 12, wherein the emulsion is stabilized at least forthe period of the dropping-in process by the use of emulsifiers.
 14. Amethod for controlling pests, wherein the liquid-core capsules accordingto claim 1 are applied to a plant stock.
 15. The method according toclaim 14, wherein the liquid-core capsules are used in a dosage ofbetween 1 to 1,000 liquid-core capsules, preferably between 10 to 500liquid-core capsules, per m² of substrate area.